The first action the test_dlbf function does is a call to the dlbf_reset function (defined in the utils_dlbf.cpp file). This function resets the dlbf_data, dlbf_coeff, and dlbf_slave PL kernels. It asserts and deasserts the DLBF_DATA_REG_OFFSET_RESET register using the Xil_Out32 function. The Xil_Out32 function is part of the AMD Hardware Abstraction Layer API in the standalone library. This API is used throughout this PS host application. See the OS and Libraries Document Collection (UG643) for the full API documentation.